Regulation Progresses of Selenium Improving Intestinal and Extra-Intestinal Tissues Health Through Regulating Gut Microbiota.

Selenium (Se) is an essential trace element that exerts pleiotropic effects on host physiology, yet the mechanisms by which it coordinates systemic health remain incompletely understood. Emerging evidence regards the gut microbiota as a key mediator of Se biological functions, giving rise to the Se-gut-tissue axis. This review synthesizes the current research progresses on how dietary Se may shape gut microbial composition and metabolism, and how these microbial shifts are associated with protective effects in both intestinal and extra-intestinal tissues. Se sources (particularly organic or new synthetic form) may bidirectionally interact with gut bacteria by enriching beneficial genera such as Akkermansia, Lactobacillus, and butyrate-producing Clostridia, while suppressing opportunistic pathogens. This microbial remodeling strengthens intestinal barrier integrity, enhances antioxidant and anti-inflammatory responses (e.g., via GPX, TrxR, and NF-κB suppression), and generates bioactive metabolites, notably short-chain fatty acids and secondary bile acids. Through these mechanisms, the Se-gut-microbiota axis may regulate distal organ homeostasis, including the liver (ameliorating NAFLD and acute injury), brain (counteracting neurodegeneration and modulating serotonin/GABA), muscle (improving mass and Se deposition), kidney (attenuating uremic toxin-induced ferroptosis), and reproductive organs. Despite encouraging progress, challenges remain in establishing causality, optimizing dose-response relationships, and translating findings into precision interventions.